Apparatus for placing a casket over a grave opening in a cemetery during a graveside service and for lowering the casket into the grave opening, or into the base portion of a burial vault in the grave opening, for interment at the conclusion of the graveside service have been known and used heretofore and among these are the casket-lowering apparatus which are disclosed in U.S. Pat. No. 2,012,367 granted Aug. 27, 1935 to Jim P. Wilkirson on "Casket Lowering Apparatus"; U.S. Pat. No. 2,588,445 granted Mar. 11, 1952 to Jim P. Wilkirson on "Casket Placer"; U.S. Pat. No. 2,762,186 granted Sept. 11, 1956 to Jim P. Wilkirson on "Casket Placer"; and the following additional prior art patents:
______________________________________ Pat. No. Patentee Title Date ______________________________________ 1,450,092 Leavitt Burial Apparatus Mar. 27, 1923 1,780,700 Cordonnier et al Coffin Lowering Nov. 4, 1930 Device 1,828,391 Canaday Casket Lowering Oct. 20, 1931 Apparatus 2,028,442 Dormer Load Handling Jan. 21, 1936 Device 2,091,909 Canaday Attachment for Aug. 31, 1937 Casket Lowering Devices 2,124,038 Lohberg Casket Support July 19, 1938 2,163,171 Haase Sectional Burial June 20, 1939 Apparatus 2,163,172 Haase Power Operable June 20, 1939 Burial Device 2,163,173 Haase Universal Burial June 20, 1939 Device 2,163,174 Haase Power Attach- June 20, 1939 ment for Burial Devices 2,285,923 Haase Winch Drag June 9, 1942 Mechanism 2,457,671 Haase Burial Apparatus Dec. 28, 1948 2,619,321 Haase Burial Unit Nov. 25, 1952 Handling Device 2,870,519 Yeazel Casket Carriage Jan. 27, 1959 3,364,536 Williams Burial Vault Jan. 23, 1968 Cover Handling Apparatus ______________________________________
However, one of the problems experienced in the use of certain of the prior art casket-placer and casket-lowering apparatus has been that the speed of the casket-lowering action of certain of such prior apparatus has commonly been controlled by flywheel speed governors and associated mechanical friction braking devices which are subject to loss of the desired friction characteristics by reason of wear, contamination of the friction members due to grease, or other contaminants, as well as mechanical weaknesses in the system, and for other reasons, with the result that the control of the speed of the casket-lowering operation by such prior art apparatus has been erratic and not capable of precise or accurate control and the operation of such prior art apparatus has been unsatisfactory.